Howto Enable and Disable ROOT Account in Ubuntu

Enabling the root account in ubuntu is rarely necessary. Almost everything you need to do as root of an Ubuntu system can be done via sudo or gksudo. If you really need a persistent root login, the best alternative is to simulate a root login shell using the following command...
$sudo -i ( same as sudo su)

To enable the root account

$ sudo passwd root

To Disable the root account

$sudo usermod -p '!' root